package Demo2;

/*
class A {

}
class B extends A {

}
final class C extends B { //密封类 不能被继承 //final int a = 10;常量

}
class D extends C {

} //erro
*/

class Student {

}
class Teacher {

}
class School { //组合
    public Student[] students;
    public Teacher[] teachers;
}
public class Test2 {
}
